﻿
#include "des.h"
#include <stdio.h>

// permuted choice table (PC1)
const static char PC1_Table[56] = {
	57, 49, 41, 33, 25, 17,  9,  1, 58, 50, 42, 34, 26, 18,
	10,  2, 59, 51, 43, 35, 27, 19, 11,  3, 60, 52, 44, 36,
	63, 55, 47, 39, 31, 23, 15,  7, 62, 54, 46, 38, 30, 22,
	14,  6, 61, 53, 45, 37, 29, 21, 13,  5, 28, 20, 12,  4
};

// permuted choice key (PC2)
const static char PC2_Table[48] = {
	14, 17, 11, 24,  1,  5,  3, 28, 15,  6, 21, 10,
	23, 19, 12,  4, 26,  8, 16,  7, 27, 20, 13,  2,
	41, 52, 31, 37, 47, 55, 30, 40, 51, 45, 33, 48,
	44, 49, 39, 56, 34, 53, 46, 42, 50, 36, 29, 32
};

// number left rotations of pc1 
const static char Shift_Table[16] = {
	1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1
};

// initial permutation (IP)
const static char IP_Table[64] = {
	58, 50, 42, 34, 26, 18, 10, 2, 60, 52, 44, 36, 28, 20, 12, 4,
	62, 54, 46, 38, 30, 22, 14, 6, 64, 56, 48, 40, 32, 24, 16, 8,
	57, 49, 41, 33, 25, 17,  9, 1, 59, 51, 43, 35, 27, 19, 11, 3,
	61, 53, 45, 37, 29, 21, 13, 5, 63, 55, 47, 39, 31, 23, 15, 7
};

// expansion operation matrix (E)
const static char E_Table[48] = {
	32,  1,  2,  3,  4,  5,  4,  5,  6,  7,  8,  9,
	 8,  9, 10, 11, 12, 13, 12, 13, 14, 15, 16, 17,
	16, 17, 18, 19, 20, 21, 20, 21, 22, 23, 24, 25,
	24, 25, 26, 27, 28, 29, 28, 29, 30, 31, 32,  1
};

// final permutation IP^-1 
const static char IPR_Table[64] = {
	40, 8, 48, 16, 56, 24, 64, 32, 39, 7, 47, 15, 55, 23, 63, 31,
	38, 6, 46, 14, 54, 22, 62, 30, 37, 5, 45, 13, 53, 21, 61, 29,
	36, 4, 44, 12, 52, 20, 60, 28, 35, 3, 43, 11, 51, 19, 59, 27,
	34, 2, 42, 10, 50, 18, 58, 26, 33, 1, 41,  9, 49, 17, 57, 25
};

// 32-bit permutation function P used on the output of the S-boxes 
const static char P_Table[32] = {
	16, 7, 20, 21, 29, 12, 28, 17, 1,  15, 23, 26, 5,  18, 31, 10,
	2,  8, 24, 14, 32, 27, 3,  9,  19, 13, 30, 6,  22, 11, 4,  25
};

// The (in)famous S-boxes 
const static char S_Box[8][4][16] = {
	// S1
	{
		{14,  4, 13,  1,  2, 15, 11,  8,  3, 10,  6, 12,  5,  9,  0,  7},
		{ 0, 15,  7,  4, 14,  2, 13,  1, 10,  6, 12, 11,  9,  5,  3,  8},
		{ 4,  1, 14,  8, 13,  6,  2, 11, 15, 12,  9,  7,  3, 10,  5,  0},
		{15, 12,  8,  2,  4,  9,  1,  7,  5, 11,  3, 14, 10,  0,  6, 13}
	},
	// S2 
	{
		{15,  1,  8, 14,  6, 11,  3,  4,  9,  7,  2, 13, 12,  0,  5, 10},
		{ 3, 13,  4,  7, 15,  2,  8, 14, 12,  0,  1, 10,  6,  9, 11,  5},
		{ 0, 14,  7, 11, 10,  4, 13,  1,  5,  8, 12,  6,  9,  3,  2, 15},
		{13,  8, 10,  1,  3, 15,  4,  2, 11,  6,  7, 12,  0,  5, 14,  9}
	},
	// S3 
	{
		{10,  0,  9, 14,  6,  3, 15,  5,  1, 13, 12,  7, 11,  4,  2,  8},
		{13,  7,  0,  9,  3,  4,  6, 10,  2,  8,  5, 14, 12, 11, 15,  1},
		{13,  6,  4,  9,  8, 15,  3,  0, 11,  1,  2, 12,  5, 10, 14,  7},
		{ 1, 10, 13,  0,  6,  9,  8,  7,  4, 15, 14,  3, 11,  5,  2, 12}
	},
	// S4 
	{
		{ 7, 13, 14,  3,  0,  6,  9, 10,  1,  2,  8,  5, 11, 12,  4, 15},
		{13,  8, 11,  5,  6, 15,  0,  3,  4,  7,  2, 12,  1, 10, 14,  9},
		{10,  6,  9,  0, 12, 11,  7, 13, 15,  1,  3, 14,  5,  2,  8,  4},
		{ 3, 15,  0,  6, 10,  1, 13,  8,  9,  4,  5, 11, 12,  7,  2, 14}
	},
	// S5 
	{
		{ 2, 12,  4,  1,  7, 10, 11,  6,  8,  5,  3, 15, 13,  0, 14,  9},
		{14, 11,  2, 12,  4,  7, 13,  1,  5,  0, 15, 10,  3,  9,  8,  6},
		{ 4,  2,  1, 11, 10, 13,  7,  8, 15,  9, 12,  5,  6,  3,  0, 14},
		{11,  8, 12,  7,  1, 14,  2, 13,  6, 15,  0,  9, 10,  4,  5,  3}
	},
	// S6 
	{
		{12,  1, 10, 15,  9,  2,  6,  8,  0, 13,  3,  4, 14,  7,  5, 11},
		{10, 15,  4,  2,  7, 12,  9,  5,  6,  1, 13, 14,  0, 11,  3,  8},
		{ 9, 14, 15,  5,  2,  8, 12,  3,  7,  0,  4, 10,  1, 13, 11,  6},
		{ 4,  3,  2, 12,  9,  5, 15, 10, 11, 14,  1,  7,  6,  0,  8, 13}
	},
	// S7 
	{
		{ 4, 11,  2, 14, 15,  0,  8, 13,  3, 12,  9,  7,  5, 10,  6,  1},
		{13,  0, 11,  7,  4,  9,  1, 10, 14,  3,  5, 12,  2, 15,  8,  6},
		{ 1,  4, 11, 13, 12,  3,  7, 14, 10, 15,  6,  8,  0,  5,  9,  2},
		{ 6, 11, 13,  8,  1,  4, 10,  7,  9,  5,  0, 15, 14,  2,  3, 12}
	},
	// S8 
	{
		{13,  2,  8,  4,  6, 15, 11,  1, 10,  9,  3, 14,  5,  0, 12,  7},
		{ 1, 15, 13,  8, 10,  3,  7,  4, 12,  5,  6, 11,  0, 14,  9,  2},
		{ 7, 11,  4,  1,  9, 12, 14,  2,  0,  6, 10, 13, 15,  3,  5,  8},
		{ 2,  1, 14,  7,  4, 10,  8, 13, 15, 12,  9,  0,  3,  5,  6, 11}
	}
};

des::des()
{
	memset(plainbits, 0, MACCIPHLEN);
	memset(subkeys, 0, 16 * 48);
	memset(ciphraw, 0, 64);
	memset(plainraw, 0, 64);
	memset(ciphinbytes, 0, 8);
	memset(plaintext, 0, 9);
	memset(ciphertext, 0, MACCIPHLEN);

	ciphertextlen = 0;
}

des::~des()
{
}

char *des::getciphbin(char *dststr)
{
	Bytes2Bits(plainbits, ciphertext, ciphertextlen);

	//将不可见ASCII码0或1加上48成为可以的字符0或1
	for (int i = 0; i < ciphertextlen; i++)
		dststr[i] = plainbits[i] + 48;

	return dststr;
}

char *des::getciphhex(char *dststr)
{
	Bits2Hex(dststr, plainbits, ciphertextlen);

	return dststr;
}

int des::initkey(const char *srcBytes)
{
	if (strlen(srcBytes) != 8)
	{
		printf("The key length is must 8.");
		return -1;
	}

	//convert 8 char-bytes key to 64 binary-bits
	char sz_64key[64] = {0};
	char tmpbuf[9];
	memset(tmpbuf, 0, 9);
	strncpy(tmpbuf, srcBytes, 8);
	tmpbuf[8] = '\0';
	Bytes2Bits(sz_64key, tmpbuf, 64);

	//PC 1
	char sz_56key[56] = {0};
	for (int k = 0; k < 56; k++)
	{
		sz_56key[k] = sz_64key[PC1_Table[k]-1];
	}

	CreateSubKey(sz_56key);

	return 0;
}

int des::CreateSubKey(char *sz_56key)
{
	char szTmpL[28] = {0};
	char szTmpR[28] = {0};
	char szCi[28] = {0};
	char szDi[28] = {0};
	memcpy(szTmpL, sz_56key, 28);
	memcpy(szTmpR, sz_56key + 28, 28);

	for (int i = 0; i < 16; i++)
	{
		//shift to left
		//Left 28 bits
		memcpy(szCi,szTmpL + Shift_Table[i],28 - Shift_Table[i]);
		memcpy(szCi + 28 - Shift_Table[i],szTmpL,Shift_Table[i]);
		//Right 28 bits
		memcpy(szDi,szTmpR + Shift_Table[i],28 - Shift_Table[i]);
		memcpy(szDi + 28 - Shift_Table[i],szTmpR,Shift_Table[i]);

		//permuted choice 48 bits key
		char szTmp56[56] = {0};
		memcpy(szTmp56, szCi, 28);
		memcpy(szTmp56 + 28, szDi, 28);

		for (int j = 0; j < 48; j++)
		{
			subkeys[i][j] = szTmp56[PC2_Table[j] - 1];
		}

		//Evaluate new szTmpL and szTmpR
		memcpy(szTmpL, szCi, 28);
		memcpy(szTmpR, szDi, 28);
	}

	return 0;
}

int des::EncryptData(const char *_srcBytes)
{
	char szSrcBits[64] = {0};
	char sz_IP[64] = {0};
	char sz_Li[32] = {0};
	char sz_Ri[32] = {0};
	char sz_Final64[64] = {0};

	Bytes2Bits(szSrcBits, _srcBytes, 64);
	//IP
	InitialPermuteData(sz_IP, szSrcBits);
	memcpy(sz_Li, sz_IP, 32);
	memcpy(sz_Ri, sz_IP + 32, 32);

	for (int i = 0; i < 16; i++)
	{
		FunctionF(sz_Li, sz_Ri, i);
	}

	//so D=LR
	memcpy(sz_Final64, sz_Ri, 32);
	memcpy(sz_Final64 + 32, sz_Li, 32);

	//~IP
	for (int j = 0; j < 64; j++)
	{
		ciphraw[j] = sz_Final64[IPR_Table[j]-1];
	}

	Bits2Bytes(ciphinbytes, ciphraw, 64);

	return 0;
}

int des::DecryptData(char *_srcBytes)
{
	char szSrcBits[64] = {0};
	char sz_IP[64] = {0};
	char sz_Li[32] = {0};
	char sz_Ri[32] = {0};
	char sz_Final64[64] = {0};
	Bytes2Bits(szSrcBits, _srcBytes, 64);
	//IP --- return is sz_IP
	InitialPermuteData(sz_IP, szSrcBits);
	//divide the 64 bits data to two parts
	memcpy(sz_Ri, sz_IP, 32); //exchange L to R
	memcpy(sz_Li, sz_IP + 32, 32);  //exchange R to L

	//16 rounds F and xor and exchange
	for (int i = 0; i < 16; i++)
	{
		FunctionF(sz_Ri, sz_Li, 15 - i);
	}

	memcpy(sz_Final64, sz_Li, 32);
	memcpy(sz_Final64 + 32, sz_Ri, 32);
	// ~IP
	for (int j = 0; j < 64; j++)
	{
		plainraw[j] = sz_Final64[IPR_Table[j]-1];
	}

	Bits2Bytes(plaintext, plainraw, 64);
	plaintext[8] = '\0';

	return 0;
}

void des::FunctionF(char *sz_Li, char *sz_Ri, unsigned int iKey)
{
	char sz_48R[48] = {0};
	char sz_xor48[48] = {0};
	char sz_P32[32] = {0};
	char sz_Rii[32] = {0};
	char sz_Key[48] = {0};
	char s_Compress32[32] = {0};
	memcpy(sz_Key, subkeys[iKey], 48);
	ExpansionR(sz_48R, sz_Ri);
	XOR(sz_48R, sz_Key, 48, sz_xor48);

	CompressFuncS(s_Compress32, sz_xor48);
	PermutationP(sz_P32, s_Compress32);
	XOR(sz_P32, sz_Li,32, sz_Rii);
	memcpy(sz_Li, sz_Ri, 32);
	memcpy(sz_Ri, sz_Rii, 32);
}

void des::InitialPermuteData(char *_dst, char *_src)
{
	//IP
	for (int i = 0; i < 64; i++)
	{
		_dst[i] = _src[IP_Table[i] - 1];
	}
}

void des::ExpansionR(char *_dst, char *_src)
{
	for (int i = 0; i < 48; i++)
	{
		_dst[i] = _src[E_Table[i] - 1];
	}
}

void des::XOR(char *szParam1,char *szParam2, unsigned int uiParamLength, char *szReturnValueBuffer)
{
	for (unsigned int i = 0; i< uiParamLength; i++)
	{
		szReturnValueBuffer[i] = szParam1[i] ^ szParam2[i];
	}
}

void des::CompressFuncS(char *_dst32, char *_src48)
{
	char bTemp[8][6];
	memset(bTemp, 0, 8 * 6);
	char dstBits[4];
	memset(dstBits, 0, 4);

	for (int i = 0; i < 8; i++)
	{
		memcpy(bTemp[i], _src48+i * 6, 6);
		int iX = (bTemp[i][0]) * 2 + (bTemp[i][5]);
		int iY = 0;
		for(int j = 1; j < 5; j++)
		{
			iY += bTemp[i][j] << (4-j);
		}

		Int2Bits(dstBits, S_Box[i][iX][iY]);
		memcpy(_dst32 + i  * 4, dstBits, 4);
	}
}

void des::PermutationP(char *_dst, char *_src)
{
	for (int i = 0; i < 32; i++)
	{
		_dst[i] = _src[P_Table[i] - 1];
	}
}

void des::Bytes2Bits(char *dstBits, const char *srcBytes, unsigned int sizeBits)
{
	for (unsigned int i = 0; i < sizeBits; i++)
		dstBits[i] = ((srcBytes[i >> 3] << (i & 7)) & 128) >> 7;
}

void des::Bits2Bytes(char *dstBytes, const char *srcBits, unsigned int sizeBits)
{
	memset(dstBytes, 0, sizeBits >> 3);
	for (unsigned int i = 0; i < sizeBits; i++)
		dstBytes[i >> 3] |= (srcBits[i] << (7 - (i & 7)));
}

void des::Int2Bits(char *dstBits, unsigned int _src)
{
	for(unsigned int i = 0; i < 4; i++)
		dstBits[i] = ((_src << i) & 8) >> 3;
}

void des::Bits2Hex(char *dstHex, char *srcBits, unsigned int sizeBits)
{
	memset(dstHex, 0, sizeBits >> 2);
	for (unsigned int i = 0; i < sizeBits; i++)		// convert to int 0-15
		dstHex[i >> 2] += (srcBits[i] << (3 - (i & 3)));

	unsigned int len = sizeBits >> 2;
	for (unsigned int j = 0; j < len; j++)
		dstHex[j] += dstHex[j] > 9 ? 55 : 48;		// convert to char '0'-'F'
	dstHex[len] = '\0';
}

void des::Hex2Bits(char *dstBits, char *srcHex, unsigned int sizeBits)
{
	memset(dstBits, 0, sizeBits);
	for (unsigned int i = 0; i < sizeBits; i++)
		srcHex[i] -= srcHex[i] > 64 ? 55 : 48; //convert to char int 0-15

	unsigned int len = sizeBits << 2;
	for (unsigned int j = 0; j < len; j++) 
		dstBits[j] = ((srcHex[j >> 2] << (j & 3)) & 15) >> 3;
}

char *des::getciphraw(char *str)
{
	memcpy(str, ciphertext, ciphertextlen >> 3);

	return str;
}

int des::DESencrypt(const char *_srcBytes, unsigned int _bytesLength)
{
	if (strlen(_srcBytes) == 0 || _srcBytes == NULL)
	{
		printf("[%s:%d]: src string input error.\n", __FILE__, __LINE__);

		return -1;
	}

	int parts = _bytesLength >> 3;
	int residue = _bytesLength % 8;

	if (residue == 0)
		ciphertextlen = parts << 6;
	else
		ciphertextlen = ((parts + 1) << 6);

	if (_bytesLength == 8)
	{
		EncryptData(_srcBytes);
		memcpy(ciphertext, ciphinbytes, 8);
		ciphertext[8] = '\0';
	}
	else if (_bytesLength < 8)
	{
		char _temp8bytes[8] = {0};
		memcpy(_temp8bytes, _srcBytes, _bytesLength);
		EncryptData(_temp8bytes);
		memcpy(ciphertext, ciphinbytes, 8);
		ciphertext[8] = '\0';
	}
	else if (_bytesLength > 8)
	{
		char szLast8Bits[8] = {0};
		for (int i = 0; i < parts; i++)
		{
			memcpy(szLast8Bits, _srcBytes + (i << 3), 8);
			EncryptData(szLast8Bits);
			memcpy(ciphertext + (i << 3), ciphinbytes, 8);
		}

		memset(szLast8Bits, 0, 8);
		memcpy(szLast8Bits, _srcBytes + (parts << 3), residue);

		EncryptData(szLast8Bits);
		memcpy(ciphertext + (parts << 3), ciphinbytes, 8);
		ciphertext[((parts + 1) << 3)] = '\0';
	}

	return 0;
}

int des::DESdecrypt(char *dst, char *_srcBytes, unsigned int _bytesLength, enuciph type)
{
	if (dst == NULL)
	{
		printf("[%s:%d] dest pointer error.\n", __FILE__, __LINE__);
		return -1;
	}

	if (type == ECIPHBIN)
	{
		printf("BIN.\n");
		for (unsigned int i = 0; i < _bytesLength; i++)
			ciphbits[i] = _srcBytes[i] - 48;
		Bits2Bytes(ciphertext, ciphbits, _bytesLength);
		ciphertextlen = _bytesLength;
	}
	else if (type == ECIPHHEX)
	{
		printf("HEX.\n");
		Hex2Bits(ciphbits, _srcBytes, _bytesLength);
		Bits2Bytes(ciphertext, ciphbits, _bytesLength << 2);
		ciphertextlen = _bytesLength << 2;
	}
	else if (type == ECIPHRAW)
	{
		printf("RAW.\n");
		memcpy(ciphertext, _srcBytes, _bytesLength);
		ciphertext[_bytesLength] = '\0';
		ciphertextlen = _bytesLength;
	}
	else
	{
		return 1;
	}

	int parts = ciphertextlen >> 6;
	int residue = ciphertextlen % 8;

	if (_bytesLength == 8)
	{
		char _temp8bytes[8] = {0};
		memcpy(_temp8bytes, _srcBytes, 8);
		DecryptData(_temp8bytes);
		strncpy(dst, plaintext, 8);
		dst[8] = '\0';
	}
	else if (_bytesLength < 8)
	{
		char _temp8bytes[8] = {0};
		memcpy(_temp8bytes, _srcBytes, 8);
		DecryptData(_temp8bytes);
		strncpy(dst, plaintext, 8);
		dst[8] = '\0';
	}
	else if (_bytesLength > 8)
	{
		char szLast8Bits[8] = {0};
		for (int i = 0; i < parts; i++)
		{
			memcpy(szLast8Bits, ciphertext + (i << 3), 8);
			DecryptData(szLast8Bits);
			strncpy(dst + (i << 3), plaintext, 8);
		}

		if (residue != 0)
		{
			memset(szLast8Bits, 0, 8);
			memcpy(szLast8Bits, ciphertext + (parts << 3), 8);
			DecryptData(szLast8Bits);
			strncpy(dst + (parts << 3), plaintext, residue);
		}
		dst[ciphertextlen >> 3] = '\0';
	}

	return 0;
}

